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steve200

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Hi, my Fronius inverter has an energy management system that sends a 12v signal to a relay/contactor when the PV array is producing a set amount of power. I intend to use it to control a 1kw immersion heater but am confused as to what specification of contactor I need. Should it be coil or solid state? I'm looking for the simplest and easiest to fit and wire in. If anyone can point me to the type I need or send me a link to where I can find it I'd be grateful. Thanks. Steve
 
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Worcester

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steve200

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Thanks Worcester - one thing I've noticed is that the relay impulse can be provided via a push button or switch, I guess that's an override facility? Do you know of any that have an indicator light to show it's operating? Thanks again. Steve
 
Hi - have a look at the Omron G7L series of relays. The 12 violt coil version draws about 140mA to operate. If you opt for the 2A version of the relay it has twin contacts rated up to 25amps at 277 vac so plenty of scope for a 1Kw immersion right up to the normal 3kW immersion
 
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Scobo

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Hi, my Fronius inverter has an energy management system that sends a 12v signal to a relay/contactor when the PV array is producing a set amount of power. I intend to use it to control a 1kw immersion heater but am confused as to what specification of contactor I need. Should it be coil or solid state? I'm looking for the simplest and easiest to fit and wire in. If anyone can point me to the type I need or send me a link to where I can find it I'd be grateful. Thanks. Steve
Hi Steve.
Just wondered what model your Fronius is ?
We have a Fronius too (IG30) although I don't think it has energy management options as far as I'm aware.

Scott.
 
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steve200

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Hi Scott, I've got the IG-TL 3.6. A software upgrade became available earlier this year to give the option. The Fronius helpline on 01908 512316 will tell you if its available for yours. Steve
 
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steve200

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Thanks for the advice guys - could you help me to understand what's best. 'Worcester' suggests the Hager latched relay and 'Brightasaspark' suggests the Omron unlatched relays. If there much of a difference? Q to 'brightasaspark' - the choice is large, is the GL7-2A-BJ the one I need and what brackets or mounting plates do I need to fit it? Thanks all. Steve
 
Hi Steve

The Omron version I would opt for is the G7L-2A-TUB. This has two plastic slotted lugs at the lower edge of its outer case which makes mounting a doddle without any further brackets/mountings etc. This relay also uses the standard 1/4" connectors and I used the yellow coloured fully shrouded crimp type quick connectors on the end of the wiring to make the necessary connections on the ones I have used.

To kill off any back e.m.f. from the relay coil affecting the switching part of the Fronius Inverter fit a diode rectifier across the relay coil with the diode anode facing the 12 volt positive supply from the Inverter. The diode is normally backed off when the relay is operated but conducts to absorb back emf as the relay switch (or whatever circuitry) in the Inverter goes open circuit to release the relay.

Hope this helps.
 
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steve200

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Many thanks for the good advice 'brightasaspark'. I looked at the RS Components range of diodes and found 4803 listed! Could you point me in the right direction of which one I need please? Thanks again. Steve
 
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steve200

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Thanks 'Brightasaspark' - could you please point me in the direction of the diode type and ratings I need?

Thanks

Steve
 
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